Nonclogging centrifugal pump



April 28, 1964 1 H. SENCE 3,130,679

NONCLOGGING CENTRIFUGAL PUMP Filed Dec. 7, 1962 2 Sheets-Sheet l April1964 H. SENCE 3,130,679

NONCLOGGING CENTRIFUGAL PUMP I Filed Dec. 7, 1962 2 Sheets-Sheet 2United States Patent O 3,130,679 NONCLOGGIING CENTRIFUGAL PUMP LeonardH. Sense, Milford, Ohio, assignor to Allis-Chalmers ManufacturingCompany, Milwaukee, Wis.

Filed Dec. 7, 1962, Ser. No. 243,112 9 Claims. (Cl. 103-103) Thisinvention relates generally to centrifugal pumps. More specifically thisinvention relates to non-clogging, solids handling centrifugal pumps.

There has long been a problem in the hydraulic industry in connectionwith pumping solid material or fibrous material. These materials tend toclog the impeller of a centrifugal pump. However, there is a trendtoward pumping more and larger solid material suspended in liquids. Onpway of solving this problem is to take a conventional centrifugal pumpimpeller and position it in a recessed area alongside a swirl or pumpingchamber. The impeller is spaced from the opposing wall of the pumpcasing a distance equal to the diameter of the inlet of the pump so thatany material entering the pumping chamber can be pumped outward throughthe discharge without engaging the impeller vanes. Although pumps ofthis type have been successful to a certain degree, they can onlydevelop a very limited head and their eflieiency is extremely low. As aresult, such a pump is used only where it is absolutely necessary topump solids of such a size that they frequently clog the impeller of aconventional centrifugal pump.

Applicant overcomes the problems mentioned above by providing a uniqueimpeller which permits the use of the vanes in the pumping chamber andis still capable of pumping any solid which enters the inlet of thepump. The impeller vanes are formed so that they are very narrow nearthe center of the impeller and gradually widened to extend substantiallyacross the impeller chamber near the periphery of the impeller. Thevanes are arranged so that they combine with the backplate of theimpeller and the casing to define a passageway extending from the eye ofthe impeller to its periphery which has a minimum size equal to a sphereof the same diameter as the inlet of the pump. Such a pump is trulynonclogging in that there is a continuous path through the pumpingchamber which is the equivalent size of a sphere equal to the diameterof the inlet. Furthermore, since the vanes of the impeller arepositioned in the pumping chamber, it utilizes the characteristics of atrue centrifugal pump and hence can develop heads and eflicieneiescomparable to a conventional centrifugal pump.

Therefore, it is the object of this invention to provide a new andimproved centrifugal pump.

Another object of this invention is to provide a nonclogging solidshandling pump with improved head and efliciency.

Other objects and advantages will be apparent from the followingdescription when read in connection with the accompanying drawings inwhich:

FIG. 1 is a cross sectional view of a centrifugal pump embodying theimpeller of this invention;

FIG. 2 is an end view taken along the line II--II of FIG. 1 of theimpeller of this invention; and

FIG. 3 shows an alternate embodiment of this invention in which theimpeller vanes are curved.

The pump assembly 9 illustrated in FIG. 1 comprises generally a pumpcasing 16 having an inlet 11 and a discharge 12. The casing defines animpeller or pumping chamber 13 in which an impeller 14 of this inventionis positioned. The chamber 13 has a peripheral volute 15 to gather thedischarge from the impeller and direct it into the discharge nozzle oropening 12.

The impeller 14 is connected to a shaft 17 which ex- 3,130,679 PatentedApr. 28, 1964 tends rearwardly from the pump casing 1% to a source ofpower. The shaft 17 is surrounded by a conventional shaft sleeve 16 anda suitable seal illustrated as a stufling box 18 having the usualpacking 19 and a gland 28) held in place by suitable bolts. The shaft 17is also surrounded by a bearing and bearing cartridge 23 which is inturn mounted in a bearing bracket 24. The bearing bracket is in turnconnected to the pump casing 10 and a base member 25.

The pump 9 is also equipped with a rear cover plate 28 which in thisparticular embodiment surrounds the stuffing box 13 and is positionedadjacent the rear plate or shroud 2% of the impeller 14. The rear coverplate 28 is recessed into a cylindrical neck portion 39 of the pumpcasing 10 so as to be slightly spaced from the impeller chamber 13. Therear shroud 29 of the impeller is also partially recessed into thecylindrical neck 30 so that the front edge of the shroud 2? is alignedwith the rear surface 31 of the impeller chamber 13. This is to avoidthe formation of any sharp corners or surfaces which would tend toimpede the progress of solids or fibers as they go through the impellerchamber.

The hub 39 of the impeller is provided with an axial bore 4! which isthreaded for connection to the end of the shaft 17. As shown in FIGS. 1and 2, the vanes 35 are areuately spaced around the shroud 29 and extendfrom near the center of the shroud plate 2? radially outward to itsperiphery. The thickness 42 of the vanes is substantially the samethroughout their length although it could be varied if desired. However,the depth or width 43 of the vanes 35 varies from a very narrow widthnear the hub 39 of the impeller to a maximum width near the periphery ofthe impeller at which point the vanes extend almost entirely across theimpeller chamber 13. However, in many applications it is preferred thatthe edge of the vane be spaced from the wall of the impeller chamber asuflicient distance to form a fluid passageway and thereby avoid anykind of a constriction about which stringy material such as found inpaper pulp can get caught and clog the pump.

The vanes 35, the shroud plate 29 and the wall 36 of the impellerchamber 13 combine to define a plurality of fluid impelling passages 45that extend from the inlet end of the pump to the discharge. The minimumsize of these passageways 45 is equivalent to a sphere of the samediameter as the inlet 11 of the pump. Thence, any solid materialentering the inlet of the pump can pass through one of these passagesthrough the impeller chamber into the discharge. The minimum size ofthese passages is made possible by forming the leading edge 45 of thevanes so that it curves away from the Wall of the impeller chamber nearthe hub of the impeller where the arcuate space between adjacent vanesis very small. In this area the distance between the edge 46 of the vaneand the wall 36 of the casing is substantially equal to the diameter ofthe inlet.

As the vane extends radially outward, the edge 46 of the vane curvestoward the opposing wall surface 36 of the impeller chamber. In areasradially outward from the hub, the sphere can move between adjacentvanes 35 and a portion of the sphere extends inwardly from the edge ofthe vanes toward the shroud plate 29 of the impeller. In this positionit does not require as much space between the edge 46 of the impellervane and the casing wall 36 to pass a sphere the size of the inlet. Forthis reason the edge of the vane can extend closer to the opposing wallsurface as the vane extends radially outward. The curve on the edge ofthe vanes continues until a point is reached where the distance betweenadjacent vanes is equal to the diameter of the inlet or the diameter ofthe theoretical sphere which is to be passed through the pump. At thispoint, the blades or vanes 35 could extend all the any solid which canenter the inlet of the s a es a 3 way to the opposing wall surface 36.However, as mentioned above, it is preferable to keep a sufllcientclearance between the wall surface and the tip of the vanes to avoid anyrestrictions to the flow through the pump of any solids or fiberssuspended in the liquids.

In an alternate embodiment illustrated in FIG. 3, the entire impellervanes 43 are curved backwardly as the vane extends outwardly to theperiphery or rim of the impeller. This is in accord with conventionalpractices in the manufacture of centrifugal pumps and is done to furtherimprove the hydraulic efiiciency of the pump. However, the sameconfiguration of the leading edge of the vanes that is shown in FIG. 1is carried out in this embodiment on the vanes 48. Hence, the width ofthe impeller vanes 48 near the hub is very small and gradually getslarger as the vane extends radially outward until it reaches its fullwidth near the outer periphery of the impeller.

In the preferred embodiment we have illustrated a pump having a circularvolute for collecting the fluid discharged from the impeller. However,it is obvious that this impeller could be used with a pump having aconventional or true volute type casing such as shown in FIG. 3 as wellas the circular casing. The circular or uniform clearance type of casinghas better nonclogging action.

In operation, as the impeller 14 begins to rotate, liquid with solidsentrained therein are drawn in through the inlet 11. This liquid is thenacted upon by the impeller and thrown radially outward. Any solids inthe liquid move through the impelling passages defined between the vanes35, the internal wall surface 36 of the impeller chamber and the rearshroud 29. In this way, pump can be impelled through the impeller intothe discharge without clogging the pump.

The position of the impeller 14 relative to casing wall 36 can be variedby changing the position of the bearing cartridge 23 in housing 42relative to the pump casing it). This can be done by rotating adjustingbolt or other means well known in the art. As is apparent from FIG. 1,there is sufi'icient space between the rear cover 28 of the pump andrear shroud 29 of impeller 14 to allow for some adjustment of thespacing between the impeller and its opposing wall surface.

Although but one embodiment has been illustrated and described, it willbe apparent to those skilled in the art that various modifications andchanges can be made therein without departing from the spirit of theinvention or the scope of the appended claims.

Having now particularly described and ascertained the nature of my saidinvention and the manner in which it is to be performed, I declare thatwhat I claim is:

1. A centrifugal pump comprising: a casing having walls defining animpeller chamber, said chamber having an axial inlet and a radiallyspaced discharge opening, an impeller mounted for rotation in saidchamber, said impeller having a rear shroud plate and a plurality ofarcuately spaced substantially radially extending vanes mounted thereon,said vanes extending inward to near the center of said impeller, thedepth of said vanes being smaller near the center of said impeller thannear its outer periphery, the radially outer portion of said vanesextendmg across substantially the entire width of said chamber, saidvanes being arranged on said impeller so as to define with said shroudplate and the opposing said wall of said impeller chamber a plurality ofpassages continuous from the inlet of said chamber to said outlet, theminimum size of said passages being at least equal to a sphere of thesame diameter as the width of said inlet, whereby any solid bodyentering said chamber through said inlet can be passed through saidimpeller to said discharge.

2. A centrifugal pump comprising: a casing having walls defining animpeller chamber, said chamber having an axial inlet and a radiallyspaced discharge opening,

i an impeller mounted for rotation in said chamber, said impeller havinga rear shroud plate and a plurality of arcuately spaced vanes mountedthereon, said vanes extending from the periphery of said plate radiallyinward to near the center of said impeller, the width of said vanesbeing smaller near the center of said impeller than near its outerperiphery, the radially outer portion of said vanes extending acrosssubstantially the entire width of said chamber, said vanes beingarranged on said impeller so as to define with said shroud plate and theopposing said wall-of said impeller chamber a plurality of passagescontinuous from the inlet of said chamber to said outlet, the minimumsize of said passages being at least equal to a sphere of the samediameter as the width of said inlet, whereby any solid body enteringsaid chamber through said inlet can be passed through said impeller tosaid discharge.

3. A centrifugal pump comprising: a casing having walls defining animpeller chamber having an axial inlet, said chamber having a peripheraluniform clearance volute connected to a discharge nozzle, an impellermounted for rotation in said chamber, said impeller having a rear shroudplate and a plurality of arcuately spaced substantially radiallyextending vanes mounted thereon, said vanes extending inward to near thecenter of said impeller, the depth of said vanes being smaller near thecenter of said impeller than near its outer periphery, the radiallyouter portion of said vanes extending across substantially the entirewidth of said chamber, said vanes being arranged on said impeller so asto define with said shroud plate and the opposing said wall of saidimpeller chamber a plurality of passages continuous from the inlet ofsaid chamber to said outlet, the minimum size of said passages being atleast equal to a sphere of the same diameter as the width of said inlet,whereby any solid particle entering said chamber can be passed throughsaid impeller to said discharge.

4. A centrifugal pump comprising: a casing having walls defining animpeller chamber having an axial inlet, said chamber having peripheralgradually increasing clearance volute terminating in a discharge nozzle,an impeller mounted for rotation in said chamber, said impeller having arear shroud plate and a plurality of arcuately spaced substantiallyradially extending vanes mounted thereon, said vanes extending inward tonear the center of said impeller, the depth of said vanes being smallernear the center of said impeller than near its outer periphery, theradially outer portion of said vanes extending across substantially theentire width of said chamber, said vanes being arranged on said impellerso as to define with said shroud plate and the opposing said wall ofsaid impeller chamber a plurality of passages continuous from the inletof said chamber to said outlet, the minimum size of said passages beingat least equal to a sphere of the same diameter as the width of saidinlet, whereby any solid particle entering said chamber can be passedthrough said impeller to said discharge.

5. A centrifugal pump comprising: a casing having walls defining animpeller chamber, said chamber having an axial inlet and a radiallyspaced discharge opening, an impeller mounted for rotation in saidchamber, said impeller having a rear shroud plate and a plurality ofarcuately spaced substantially radially extending vanes mounted thereon,said vanes extending inward to near the center of said impeller, thedepth of said vanes being smaller near the center of said impeller thannear its outer periphery, the radially outer portion of said vanesextending partially across said chamber, said vanes being arranged onsaid impeller so as to define with said shroud plate and said opposingwall of said chamber a plurality of separate passages continuous fromthe inlet of said chamber to said outlet, the minimum size of saidpassages being at least equal to a sphere of the same diameter as thewidth of said inlet, whereby any solid particle entermg said chamber canbe passed through said impeller to said discharge.

6. A centrifugal pump comprising: a casing having walls defining animpeller chamber, said chamber having an axial inlet and a radiallyspaced discharge opening, an impeller mounted for rotation in saidchamber, said impeller having a rear shroud plate and a plurality ofarcuately spaced vanes mounted thereon, said vanes extending inwardalong a curved line from the periphery of said plate to near the centerof said impeller, the width of said vanes being smaller near the centerof said impeller than near its outer periphery, the radially outerportion of said vanes extending across substantially the entire width ofsaid chamber and being arranged on said impeller so as to define withsaid shroud plate and said walls a plurality of independent passagescontinuous from the inlet of said chamber to said outlet, the minimumsize of said passages being at least equal to a sphere of the samediameter as the width of said inlet, whereby any solid body enteringsaid chamber through said inlet can be passed through said impeller tosaid discharge.

7. The centrifugal pump of claim 1 in which the tips of the vanescombined with the hub of the impeller to define a continuous smoothsurface.

8. The centrifugal pump of claim 1 in which the walls defining theimpeller chamber are substantially parallel.

9. The centrifugal pump of claim 1 in which the maximum depth of thevanes is at the outer periphery of the impeller.

References Cited in the file of this patent UNITED STATES PATENTS2,635,548 Brawley Apr. 21, 1953 2,655,868 Lindau et al Oct. 20, 19532,785,930 Burnside Mar. 19, 1957 2,853,019 Thornton Sept. 23, 19582,958,293 Pray Nov. 1, 1960 FOREIGN PATENTS 542,597 France May 19, 1922413,573 Great Britain of 1934 574,079 Great Britain Dec. 19, 1945 82,497Switzerland Oct. 1, 1919

1. A CENTRIFUGAL PUMP COMPRISING: A CASING HAVING WALLS DEFINING ANIMPELLER CHAMBER, SAID CHAMBER HAVING AN AXIAL INLET AND A RADIALLYSPACED DISCHARGE OPENING, AN IMPELLER MOUNTED FOR ROTATION IN SAIDCHAMBER, SAID IMPELLER HAVING A REAR SHROUD PLATE AND A PLURALITY OFARCUATELY SPACED SUBSTANTIALLY RADIALLY EXTENDING VANES MOUNTED THEREON,SAID VANES EXTENDING INWARD TO NEAR THE CENTER OF SAID IMPELLER, THEDEPTH OF SAID VANES BEING SMALLER NEAR THE CENTER OF SAID IMPELLER THANNEAR ITS OUTER PERIPHERY, THE RADIALLY OUTER PORTION OF SAID VANESEXTENDING ACROSS SUBSTANTIALLY THE ENTIRE WIDTH OF SAID CHAMBER, SAIDVANES BEING ARRANGED ON SAID IMPELLER SO AS TO DEFINE WITH SAID SHROUDPLATE AND THE OPPOSING SAID WALL OF SAID IMPELLER CHAMBER A PLURALITY OFPASSAGES CONTINUOUS FROM THE INLET OF SAID CHAMBER TO SAID OUTLET, THEMINIMUM SIZE OF SAID PASSAGES BEING AT LEAST EQUAL TO A SPHERE OF THESAME DIAMETER AS THE WIDTH OF SAID INLET, WHEREBY ANY SOLID BODYENTERING SAID CHAMBER THROUGH SAID INLET CAN BE PASSED THROUGH SAIDIMPELLER TO SAID DISCHARGE.